Buggy code:
public class SSBlockWallCasingRaw extends SSMetaBlock { public SSBlockWallCasingRaw ( ) { } @ Override @ SideOnly ( Side . CLIENT ) public void registerBlockIcons ( IIconRegister icon ) { } @ Override public boolean isOpaqueCube ( ) { } @ Override public String getUnlocalizedName ( ) { } @ SuppressWarnings ( { "rawtypes" , "unchecked" } ) @ Override @ SideOnly ( Side . CLIENT ) public void getSubBlocks ( Item par1 , CreativeTabs tab , List list ) { } public boolean onBlockActivated ( World world , int x , int y , int z , EntityPlayer entityplayer , int side , float a , float b , float c ) { if ( world . isRemote ) <START_BUG> return true ; <END_BUG> if ( ( entityplayer . getCurrentEquippedItem ( ) ) != null ) { if ( SS . Debug ) System . out . println ( ( ( ( "[" + ( SS . MODNAME ) ) + "]<seq2seq4repair_space>act<seq2seq4repair_space>" ) + ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) ) ) ) ; int metaData = world . getBlockMetadata ( x , y , z ) ; if ( metaData == 0 ) { if ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "item.screwdriver" ) ) { world . setBlockMetadataWithNotify ( x , y , z , 1 , 3 ) ; entityplayer . getCurrentEquippedItem ( ) . damageItem ( 1 , entityplayer ) ; return true ; } else if ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "ic2.itemToolWrench" ) ) { ItemStack itemStack = new ItemStack ( SSConfig . ssBlockWallCasingRaw , 1 , 0 ) ; world . setBlockToAir ( x , y , z ) ; StackUtil . dropAsEntity ( world , x , y , z , itemStack ) ; return true ; } } else if ( metaData == 1 ) { if ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "ic2.itemRubber" ) ) { -- ( entityplayer . getCurrentEquippedItem ( ) . stackSize ) ; world . setBlockMetadataWithNotify ( x , y , z , 2 , 3 ) ; return true ; } else if ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "item.screwdriver" ) ) { world . setBlockMetadataWithNotify ( x , y , z , 0 , 3 ) ; entityplayer . getCurrentEquippedItem ( ) . damageItem ( 1 , entityplayer ) ; return true ; } } else if ( metaData == 2 ) { if ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "item.screwdriver" ) ) { world . setBlockMetadataWithNotify ( x , y , z , 3 , 3 ) ; return true ; } else if ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "item.welder" ) ) { world . setBlockMetadataWithNotify ( x , y , z , 1 , 3 ) ; entityplayer . getCurrentEquippedItem ( ) . damageItem ( 1 , entityplayer ) ; return true ; } } else if ( metaData == 3 ) { if ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "ic2.itemPlateIron" ) ) { -- ( entityplayer . getCurrentEquippedItem ( ) . stackSize ) ; world . setBlockMetadataWithNotify ( x , y , z , 4 , 3 ) ; return true ; } else if ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "item.screwdriver" ) ) { world . setBlockMetadataWithNotify ( x , y , z , 2 , 3 ) ; entityplayer . getCurrentEquippedItem ( ) . damageItem ( 1 , entityplayer ) ; return true ; } } else if ( metaData == 4 ) { if ( ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "ic2.itemToolWrench" ) ) || ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "item.GT_Wrench_Bronze" ) ) ) { world . setBlockMetadataWithNotify ( x , y , z , 5 , 3 ) ; return true ; } else if ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "item.welder" ) ) { world . setBlockMetadataWithNotify ( x , y , z , 3 , 3 ) ; entityplayer . getCurrentEquippedItem ( ) . damageItem ( 1 , entityplayer ) ; return true ; } } else if ( metaData == 5 ) { if ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "item.welder" ) ) { world . setBlock ( x , y , z , ssBlockWallCasingC , 0 , 3 ) ; return true ; } else if ( entityplayer . getCurrentEquippedItem ( ) . getUnlocalizedName ( ) . equals ( "ic2.itemToolWrench" ) ) { world . setBlockMetadataWithNotify ( x , y , z , 4 , 3 ) ; entityplayer . getCurrentEquippedItem ( ) . damageItem ( 1 , entityplayer ) ; return true ; } } } return false ; } }

Fix:
return false ;